Where does “い言葉” come from?

い言葉 (Okinawan) comes from Japanese 言葉, from Japanese 言, from Middle Chinese 言.

Ancestry of “い言葉”, step by step

StepLanguageWordMeaning
1Japanese言葉a word, a term; language, speech
2Japanese言word; parole
3Middle Chinese言—
Every word from Middle Chinese 言 →Every word from Japanese 言 →Every word from Japanese 言葉 →